Abstract |
The aim of the present thesis was to study the psychotic spectrum disorders in terms of understanding the mechanisms of their etiology and their manifestation in high risk groups, such the first-degree relatives of patients. Neuropsychological parameters-clinical markers (endophenotypes) were examined in unaffected relatives of patients with psychotic symptomatology. More specifically, cognitive functions, such as memory, attention and processing speed, and traits of psychopathology, quality of life and functionality were studied in unaffected relatives of schizophrenia and psychotic bipolar disorder patients.
Comparisons between the group of unaffected relatives and the control group revealed that the control group a) had superior visual memory, verbal fluency, response inhibition, processing speed, working memory, cognitive flexibility and reasoning, b) had superior social functioning and tended to have higher quality of life and c) had lower score in depression and also tended to have lower somatization and anxiety, When the group of relatives was split into two sub-groups according to thediagnosis of their affected relative, it was found that a) unaffected relatives of schizophrenia patients had higher depression and somatization compared with the control group while the unaffected realtives of psychotic bipolar disorder patients had higher anxiety compared with the control group, b) unaffected relatives of psychotic bipolar disorder patients had poorer social functioning compared with the control group, c) both groups of relatives had poorer visual memory, control inhibition, working memory, cognitive flexibility and reasining, d) unaffected relatives of schizophrenia patients had poorer verbal fluency compared with the control group, e) unaffected relatives had poorer processing speed compared with both the control group and the unaffected relatives of psychotic bipolar disorder patients.
Discriminant analysis including scores in all neuropsychological tasks, psychopathology dimensions and functionality revealed two significant functions: the first function (including positive correlations with visual memory, reasoning, control inhibition, working memory, cognitive flexibility and verbal fluency) discriminated the control group from the relatives and the second function (including positive correlations with processing speed and social functioning and a negative correlation with anxiety) disciriminated between the two groups of relatives.
In support to the psychosis continuum, we found that certain cognitive functions, which are mediated by a fronto-parietal network, show linear impairments in unaffected first-degree relatives of schizophrenia and psychotic bipolar disorder patients. Processing speed and verbal fluency impairments were evident only in schizophrenia relatives. Self-perceived symptoms of depression, somatization and anxiety as well as social functioning also differ between the two disorders; the pattern of scores in depression and somatization is also in accordance with the psychosis continuum view.
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